Common [non]sense.

[Gheld]

So I was thinking the other day; about pieces of conventional 'wisdom' that people repeat back to you, that is even perpetuated by many official agencies, but you just know to be incorrect. It seems like it would be a fun list to compile:

Something that you've heard from more than one different source, that is touted as wisdom, but through your own education/training/professional experience you know to be complete rubbish. Please don't submit political views or conspiracy theories, I'm talking little every day things that you usually don't think twice about.

It gives you a chance to rant about something that maybe irks you when you hear it constantly.

My submission (and format guideline).

Frost-free/auto defrost/no frost freezers and meat.

The common (non)sense surrounding it

Meat freezer burns if you put it on a frost-free freezer. This is 'because the freezer thaws every so often in order to keep ice from building up.' While others blame 'moisture being lost to air circulation.'

The facts:

When a 'frost free' freezer goes into its defrost cycle the evaporator coil does indeed heat up above freezing temperature. However it is only the evaporator coil that is heated. So unless your meat is placed directly on the evap. coil (which is impossible) collateral heating of the food will be minimal at best, a frost-free freezer will never heat food above the freezing temperature during the defrost cycle if it is in proper working order.
A frost-free freezer does also utilize air circulation in order to reduce moisture build-up in the cooling compartment. However even if air was not circulating unsealed food would still lose moisture at a predictable rate due to sublimation (water going directly from its frozen state into a gaseous state). The best way to prevent this moisture loss is by packaging frozen foods properly (i.e. in air-tight freezer bags or vacuum packaging).

The real nail in the coffin for this is the fact that modern cold storage facilities utilize the exact same methods (air circulation, and evap. coil heating) to reduce frost buildup, because when you are talking about a freezer hundreds of thousands (even millions) of cubic feet in volume which requires 24/7 operation; manual defrosting is NOT an option, and any frost buildup will insulate your food from the evap. coil, reducing the efficiency of your freezer significantly. So your food that you are taking home has probably already spent plenty of time inside a frost-free freezer.

How I know this:

I'm a refrigeration engineer at a cold storage facility.

[Decagon]

Not sure if this applies, but I find it annoying when people say "Hey, you work with computers, right? Can you fix my Stereo/DVD player/TV/ipod/lamp/phone." I would have thought that it was common knowledge that not all electrical devices fall under computer or computer related devices but I guess it's just the opposite.